JP5241575B2 - Induction heating cooker - Google Patents

Description

  The present invention relates to an induction heating cooker.

  The induction heating cooker includes a top plate on which a pan or the like is placed on an upper surface portion of a main body, and an annular heating coil and its drive circuit are configured in the main body. The induction heating cooker is a cooker that performs cooking by causing a high-frequency current to flow through a heating coil, generating an eddy current in the pan by the generated high-frequency magnetic field, and heating the pan itself by Joule heat generated by the eddy current.

  A conventional induction heating cooker detects the temperature at the bottom of the pan with a heat sensitive element such as a thermistor in contact with the lower surface of the top plate on which the pan is placed. However, the top plate is made of crystallized glass with low thermal conductivity, and a time delay occurs until the temperature of the pan bottom reaches the lower surface of the top plate. The thermistor does not detect the temperature at the bottom of the pan directly, but indirectly detects the temperature at the bottom of the pan by detecting the temperature at the bottom of the top plate. It was not possible to detect with high response.

  Therefore, what detects the temperature of a pan bottom by detecting the infrared rays radiated | emitted from a pan bottom with an infrared sensor directly through a top plate is proposed (for example, patent document 1, patent document 2).

JP 2008-311000 A JP 2009-26570 A

  However, in the induction heating cooker of patent document 1 and patent document 2, the infrared sensor is provided in the center of the coil, and when there is uneven heating in the temperature of the pan bottom, it is difficult to measure the maximum temperature of the pan bottom. There was a problem that there was. For this reason, when maintaining the temperature of the frying pan at the time of fried food, it may not be possible to maintain the appropriate temperature.

  The present invention addresses the above-described problems, and provides an induction heating cooker provided with a pan temperature detecting means capable of quickly detecting the vicinity of the maximum temperature of the pan on the top plate, and further realizing a control method for maintaining an appropriate temperature appropriately. The purpose is to do.

The above-described problems are provided in a top plate on which an object to be heated is placed, a heating coil having a concentric gap between an inner peripheral coil and an outer peripheral coil, and the concentric gap. A light shielding cylinder that guides the infrared rays radiated from the object to be heated downward, an infrared sensor module that outputs a voltage value corresponding to the amount of infrared rays via the light shielding cylinder, and an output voltage value from the infrared sensor module A temperature calculation circuit that calculates the temperature of the object to be heated based on the high frequency current supply circuit that supplies a current to the heating coil, and a control circuit that controls the high frequency current supply circuit based on an output of the temperature calculation circuit; a plurality of heating power setting key for inputting a heating power of said heating coils, a plurality of lamps which are provided corresponding to the respective heating power setting keys, the provided, the outer circumference of the inner circumferential side coil from the coil center The inner circumference of the outer peripheral coil is provided at a distance of approximately 55 mm from the coil center, and the light shielding cylinder is provided at a distance of 45 to 55 mm from the coil center. When the temperature of the object to be heated calculated by the temperature calculation circuit reaches a predetermined temperature , the circuit notifies the user that the temperature has reached an appropriate temperature, and also blinks the plurality of lamps simultaneously. The induction heating cooker that controls the high-frequency current supply circuit to maintain the predetermined temperature while prompting the user to input the thermal power setting key and prompting the user to input thermal power is solved. it can.

  According to the present invention, it is possible to quickly detect the vicinity of the maximum temperature of the pan on the top plate, and to appropriately maintain the appropriate temperature.

The external appearance perspective view of the induction heating cooking appliance of Example 1. FIG. The heating coil top view of the induction heating cooking appliance of Example 1. FIG. The heating coil bottom view of the induction heating cooking appliance of Example 1. FIG. Sectional drawing of the induction heating cooking appliance of Example 1. FIG. The functional block diagram of the pot heating control system of the induction heating cooking appliance of Example 1, and sectional drawing of an infrared detection module. The heating coil top view of the conventional induction heating cooking appliance. The pan heating distribution map by the heating coil of the conventional induction heating cooker. The sensor position schematic diagram of the induction heating cooking appliance of Example 1. FIG. The sensor position schematic diagram of the induction heating cooking appliance of Example 1. FIG. The pan heating distribution map by the heating coil of the induction heating cooking appliance of Example 1. FIG. It is explanatory drawing which shows the upper surface operation part right and the upper surface display part right. It is explanatory drawing which shows the state of the upper surface operation part right and the upper surface display part right during preheating with a stir-fried thing. It is explanatory drawing which shows the state of the upper surface operation part right of a fried food, and the upper surface display part right. It is explanatory drawing which shows the state of the upper surface operation part right and the upper surface display part right in the middle of frying. It is explanatory drawing which showed the relationship between the detection temperature of a pan bottom, and a thermal power. It is explanatory drawing which showed the relationship between the detection temperature of a pan bottom, and a thermal power. It is a figure explaining the detail of the suitable temperature maintenance control of a to-be-heated material.

  Embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is an external perspective view of the induction heating cooker according to the first embodiment. In FIG. 1, 101 is a main body of the induction heating cooker, 102 is an operation unit for turning on / off the power, setting heating, and the like, 103 is a display operation unit, and includes an upper surface operation unit 9 and an upper surface display unit 10. Reference numeral 104 denotes a top plate on which a pan or the like made of heat-resistant glass or the like is placed and has transparency in the infrared region. 105 to 107 are heating areas in which a heating coil for induction heating of a pan or the like is installed below, 108 to 110 are infrared transmission areas that transmit infrared rays radiated from the bottom of the pot below the top plate 104, and 111 is provided in the main body 101. This is a cooling air suction port for cooling the circuits and the like.

  FIG. 2 is a top view of the vicinity of the heating coil 200 below the heating region 106. The heating coil 200 is composed of an inner peripheral coil 201 and an outer peripheral coil 202 provided on the same plane with a concentric gap G interposed therebetween, so that current in the same direction flows through both coils. The outer end of the side coil 201 and the inner end of the outer peripheral side coil 202 are electrically connected. In this embodiment, the inner peripheral coil 201 is provided at a distance of about 30 to 45 mm from the coil center, and the outer peripheral coil 202 is provided at a distance of about 55 to 90 mm from the coil center. . 203 is a coil base for holding the heating coil 200, 204 is a detection area of an infrared sensor module provided at a distance of 45 to 55 mm from the center of the coil, and infrared rays emitted from the bottom of the pan are sent to an infrared sensor module 407 to be described later. This is the guiding area. In this embodiment, the size of the detection area 204 of the infrared sensor module is about 10 mm in diameter. Reference numerals 205 to 208 denote thermistors (contact temperature sensors) for measuring the temperature of the lower surface of the top plate 104.

  FIG. 3 is a bottom view of the coil base 203. In FIG. 3, reference numerals 301 to 312 are radially provided ferrite cores for efficiently inputting the magnetic field generated by the heating coil 200 to the pan on the top plate 104. The pitch between the ferrite cores 301 and 302 is larger than the pitch of other ferrite cores in order to provide the detection area 204 of the infrared sensor module.

  4 is a cross-sectional view of the main body taken along the plane AA ′ of FIG. In FIG. 4, 401 is a cooling fan, 402 is a motor that drives the cooling fan 401, 403 to 405 are high-frequency current supply circuits that supply predetermined power to the heating coil 200, and 406 is cooling air sucked by the cooling fan 401. An arrow 407 indicating a flow is an infrared sensor module. The coil base 203 is in close contact with the lower surface of the top plate 104 by a spring (not shown).

  FIG. 5 is a functional block diagram showing the pan heating control system. In FIG. 5, reference numeral 501 denotes a pan that is an object to be heated, 502 a temperature calculation circuit that calculates the temperature of the pan 501 based on outputs of the infrared sensor module 407 and the thermistors 205 to 208, and 503 according to the output of the temperature calculation circuit 502 The control circuit controls the high-frequency current supply circuit 405 and the power supplied to the heating coil 200. Reference numeral 508 denotes a light shielding cylinder that guides the infrared rays emitted from the pan 501 to the lower infrared sensor module 407 and prevents the infrared rays emitted from the heating coil 200 from entering the infrared sensor module 407. Reference numeral 34 is a menu setting key for selecting a menu to be used from among a plurality of automatic menus incorporated in advance. 31 is a heating power setting key which allows the user to adjust the heating power according to his / her preference. The upper surface display unit 10 displays a menu selected by the menu setting key 34, displays the progress of automatic cooking, and the setting contents of the heating power setting key 31.

  Next, the configuration of the infrared sensor module 407 will be described. In the cross-sectional view of the infrared sensor module 407, reference numeral 504 denotes a thermopile that is a kind of thermal infrared detection element. Reference numeral 505 denotes a windproof case incorporating a thermopile 504, which is made of a resin having low thermal conductivity in order to prevent a sudden change in the ambient temperature of the thermopile 504. Reference numeral 506 denotes a windproof window provided on the upper surface of the windproof case 505 to make the windproof case 505 an airtight structure, which transmits infrared rays from the pan 501 and radiates the top plate 104 warmed by heat transfer from the pan 501. Cuts infrared rays (5 microns or more) having a high temperature-raising effect and suppresses temperature rise in the windproof case 505.

  Reference numeral 507 denotes an infrared transmitting member, which is obtained by processing the same material as the top plate 104 into a lens shape. That is, since the wavelength transmission characteristics of the infrared transmitting member 507 are the same as those of the top plate 104, infrared rays having a wavelength transmitted through the top plate 104 among infrared rays emitted from the pan 501 are also transmitted through the infrared transmitting member 507. On the other hand, infrared light having a wavelength cut by the top plate 104 is also cut by the infrared transmitting member 507. Infrared rays radiated from the lower surface of the top plate 104 that has become hot due to heat transfer from the pan 501 also reach the infrared transmitting member 507, but most of the infrared rays are infrared rays having a wavelength that is cut by the infrared transmitting member 507. Therefore, most of infrared rays emitted from the top plate 104 are cut by the infrared transmitting member 507. That is, most of the infrared rays reaching the thermopile 504 are infrared rays emitted from the pan 501 and the influence of the infrared rays emitted from the top plate 104 is small. it can.

  Next, the operation of this embodiment will be described. When the user places the pan 501 on the top plate 104 and operates the upper surface operation unit 9 to start heating, the control circuit 503 controls the high-frequency current supply circuit 405 to supply predetermined power to the heating coil 200. When a high-frequency current is supplied to the heating coil 200, an induction magnetic field is generated from the heating coil 200, and an eddy current is generated in the pan on the top plate to be induction heated. This induction heating raises the temperature of the pan, and the food in the pan is cooked.

  In general, an object itself emits infrared rays according to its temperature. The intensity of the infrared rays increases with the temperature of the object. Therefore, if the amount of infrared rays emitted from the pan is measured using the infrared sensor module, the temperature of the pan can be measured instantaneously.

  The problem here is that when induction heating is performed using a heating coil, the temperature at the bottom of the pan does not become uniform, so even if an infrared sensor module is used, the maximum temperature at the bottom of the pan may not be accurately measured. . The temperature measurement by the infrared sensor in the conventional induction heating cooker is demonstrated using FIG. 6, FIG. FIG. 6 is a top view of the vicinity of a conventional heating coil, in which 601 is an integrated heating coil formed at a distance of about 36 mm to about 88 mm from the coil center, and 602 is provided at a position about 15 mm from the coil center. It is a detection area of an infrared sensor module. FIG. 7 shows that when the heating coil 601 is used to heat a stainless steel pan having a relatively thin bottom with high heating power, the maximum temperature of the pan bottom surface temperature reaches about 360 ° C. (ignition temperature of tempura oil). Was measured at a distance of 10 mm from the coil center. As can be seen from FIG. 7, the minimum temperature at the bottom of the pan is about 30 ° C. near the center, and the maximum temperature at the bottom of the pan is about 350-360 ° C. near a distance of 50 to 70 mm from the coil center. That is, the temperature difference between the lowest temperature and the highest temperature is about 330 ° C. This is because the integrated coil 601 has a donut shape, and on the principle of induction heating, the pot portion on the heating coil has the largest eddy current and the temperature rises greatly. This is because the temperature rise is small because the current is small. In the detection area 602 of the conventional infrared sensor module provided at a position about 15 mm from the coil center, only a pot bottom temperature of about 60 ° C. could be observed. That is, the temperature difference between the maximum temperature and the observed temperature reached about 270 ° C.

  In the induction heating cooker of this embodiment, in order to measure the pan bottom temperature at a distance of 50 to 70 mm from the center of the coil where the pan bottom temperature becomes maximum, as shown in FIG. The infrared coil is divided into outer peripheral coils 202, and an infrared sensor module detection area 204 is provided at a distance of 50 mm from the coil center. The detection area 204 provided at a distance of 50 mm from the coil center is a position included in the position of 50 to 70 mm from the coil center where the pan bottom temperature is highest, and at the same time, as shown in FIG. Even when heating a small-diameter pan with the smallest diameter of 120 mm among the high pans, the pan bottom can completely cover the detection area 204 of the infrared sensor module, and the temperature of the pan bottom can be measured. is there.

  FIG. 10 shows a case where a heating pot 200 is used to heat a stainless steel pan having a relatively thin bottom with high heating power, and when the highest point of the pan bottom surface temperature reaches about 360 ° C. (ignition temperature of tempura oil). Was measured at a distance of 10 mm from the coil center. As can be seen from FIG. 10, the minimum temperature at the bottom of the pan is about 50 ° C. near the center, and the maximum temperature at the bottom of the pan is about 360 ° C. near a distance of 70 mm from the center of the coil. The pan bottom temperature observed at a position of about 50 mm from the coil center where the detection area 204 is provided is about 320 ° C. That is, if the configuration of the present embodiment is used, the temperature difference between the maximum temperature and the observed temperature can be only about 40 ° C., and the thermal power control based on the observed temperature can be suitably performed.

  In addition, when the space | interval G of the inner peripheral side coil 201 shown in FIG. 2 and the outer peripheral side coil 202 is wide, since the pan bottom temperature on the detection area 204 will fall, the space | interval G is so good that it is narrow, but when the space | interval G is made too narrow. The detection area is also narrowed, and infrared rays emitted from the pan bottom cannot be sufficiently captured. Therefore, it is desirable to set the gap G to a certain extent to about 10 to 20 mm. In this embodiment, the gap G is set to 15 mm.

  Further, as shown in FIG. 3, the thermistor 205 is installed next to the ferrite core 301 next to the detection area 204, and the thermistors 206 and 207 are arranged so as to form a substantially equilateral triangle by the thermistors 205 to 207. The thermistor 208 is arranged at the center of the equilateral triangle. As a result, as shown in Fig. 9, even if the 120mm diameter pan bottom moves within the circle of 200mm diameter, which is the coil heating range, there are always multiple thermistors under the pan bottom, so the temperature at the pan bottom can be detected. It becomes. If there is no infrared sensor module detection area 204 below the bottom of the pan, high heating power input is not performed and relatively slow heating control is performed.

  As described above, according to the induction heating cooker of the present embodiment, the vicinity of the maximum temperature of the pan on the top plate can be detected quickly, so that the temperature of the pan can be controlled safely.

  Next, the appropriate temperature maintenance control using the induction heating cooker of the present embodiment will be described with reference to FIG. In FIG. 5, the control circuit 503 controls the heating power, the heating time, and the temperature of the pan 501 based on the procedures and rules incorporated in advance with the menu input with the menu setting key 34. The high frequency current supply circuit 405 is controlled based on the temperature detected by the calculation circuit 502 to heat the pan 501, or the high frequency current supply circuit 405 is controlled to heat the pan 26 with the thermal power input by the thermal power setting key 31. The menu input by the menu setting key 34, the progress of cooking, and the content input by the heating power setting key 31 are displayed on the upper surface display unit 10. In addition, the upper surface display part 10 shall be comprised by the display 41a and the display 41b which are mentioned later, and the lamp | ramps 35-40. The upper surface operation unit 9 includes an upper surface operation unit right 9a for inputting the heating power of the right heating region 106, an upper surface operation unit left 9b for inputting the heating power of the left heating region 105, and an upper surface operation unit for inputting the heating power of the central heating region 107. It consists of the center 9c.

  The upper surface display unit 10 is arranged as an upper surface display unit right 10a, an upper surface display unit left 10b, and an upper surface display unit center 10c corresponding to each operation unit of the upper surface operation unit 9, and displays the contents input by each operation unit.

  Next, FIG. 11 is an explanatory diagram showing the upper surface operation unit right 9a and the upper surface display unit right 10a corresponding to the right heating region 106. The display means 17, the heating power setting key 31, and the menu setting key 34 will be described in detail using the upper surface operation unit right 9a and the upper surface display unit right 10a.

  Since the contents related to the present invention are the same for the upper surface operation section right 9a and the upper surface display section right 10a, the upper surface operation section left 9b and the upper surface display section left 10b, and the upper surface operation section center 9c and the upper surface display section center 10c, the upper surface operation section left 9b and the upper surface A description of the display unit left 10b, the upper surface operation unit center 9c, and the upper surface display unit center 10c side is omitted.

  The upper right display portion 10a is divided into a display 41a and a display 41b. The display 41a displays the thermal power input by the thermal power setting key 31, the menu input by the menu setting key 34, and the like. In the display 41b, the menu input by the menu setting key 34 is used. Preheating the pan and the frying pan so that when the temperature of the pan and the frying pan reaches an appropriate temperature, the timing of adding the ingredients can be notified. Display “appropriate temperature”.

  The lamps 35 to 40 are composed of LEDs or the like, and the lamp 35 is lit when a turn-off / start key 30 described later is pressed and a heating start is input. The lamps 36 to 39 are lit with the thermal power set by the thermal power setting key 31 described later. Further, the lamps 36 to 39 are simultaneously flashed and notified to prompt the user to set the heating power by automatic cooking which will be described later. The lamp 40 blinks and notifies when the thermal power adjustment key 32 is valid.

  The thermal power that can be set with the thermal power setting key 31 is divided into four stages, a “slow fire” key 31a, a “low fire” key 31b, a “medium fire” key 31c, and a “high fire” key 31d, and the necessary thermal power can be input in one operation. In this way, keys are provided individually according to the thermal power. The standard of each thermal power is, for example, when a maximum of 12 stages of thermal power is provided, the relationship between each thermal power and power consumption is equivalent to 100W for "1" stage, equivalent to 200W for "2" stage, 300W for "3" stage, “4” stage is 400 W, “5” stage is 500 W, “6” stage is 800 W, “7” stage is 1.1 kW, “8” stage is 1.4 kW, “9” stage is 1.6 kW, “10” "Is 2 kW," 11 "is 2.5 kW, and" 12 "is 3 kW. The numbers at each stage are the numbers displayed on the display 41a as a guide for the thermal power. In addition, the relationship between the four-stage thermal power display and the 12-stage display is “1” for “slow fire”, “2”, “3”, “4”, “5” for “low fire”, and “6” for “medium fire”. ”,“ 7 ”,“ 8 ”, and“ High fire ”are“ 9 ”and“ 10 ”, which are not provided in the key of the heat setting key 31, but“ 11 ”and“ 12 ”are assigned as“ high power ”. . The heat setting key 31 is “1” for the “slow fire” key 31a, “4” for the “low heat” key 31b, and “7” for the “medium fire” key 31c so that it can be directly input to the representative fire power of the four stages of fire power. ”,“ High fire ”key 31 d can input“ 10 ”firepower.

  When the thermal power adjustment key 32 inputs a thermal power that cannot be input by the thermal power setting key 31, for example, thermal power "9", the thermal power is first input to "7" by the "medium fire" key 31c, and then the thermal power adjustment UP key 32b. When the key is pressed twice, the number indicating the heating power displayed on the display 41a is changed from “7” to “8” and from “8” to “9”, indicating that the heating power is changed to “9”. . Incidentally, the thermal power can be lowered from “9” to “8” by pressing the thermal power adjustment DOWN key 32a next time.

  Reference numeral 33 denotes a timer key for selecting a heating time mainly when performing timer cooking such as stew or heat retention. The menu setting key 34 is for selecting cooked rice, fried food, kettle, fried food, etc. for automatic cooking. When the menu setting key 34 is pressed, the menu is displayed on the display 41a. The menu is switched and displayed. This selects the menu to be used. Reference numeral 48 denotes a cut / start key for starting and stopping cooking.

  The present embodiment has the above-described configuration. Next, the operation will be described with reference to FIGS. 12 to 14 are display examples of the upper surface operation unit and the upper surface display unit during automatic cooking. FIG. 15 and FIG. 16 are diagrams showing the relationship between the detected temperature of the pot bottom, the heating power, and the operation.

  For example, when a user cooks a fried vegetable, the user places a frying pan on the mounting portion used for heating, and presses the menu setting key 34 while viewing the display 41a to select the menu “stir fry”. . When the menu is selected, the lamp 35 blinks to notify that the OFF / START key 30 has been activated. When the OFF / START key 30 is pressed, cooking is started, and the lamp 35 is turned on from flashing to indicate that cooking is in progress (preheating). Then, a display indicating that the frying pan is currently being preheated lights up “in preheating” on the display means 41b. The state of the display 41 and the lamps 35 to 40 at this time is shown in FIG.

  Next, when heating of the frying pan proceeds and the detected temperature at the bottom of the frying pan approaches an appropriate temperature range, the heating power is reduced to reduce the overshoot of the frying pan temperature (FIGS. 15 (a) and 16 (a)). When the detection temperature of the frying pan reaches the appropriate temperature range, the user is notified of the appropriate temperature. Therefore, the display of “Preheating” on the display 41b is redisplayed as “appropriate temperature”, and the fact that the appropriate temperature has been reached is also notified by a buzzer or voice.

  Then, the ingredients to be fried are put into the frying pan, and the four lamps of the lamp 36 to the lamp 39 of the display means 17 are simultaneously flashed to perform a prompting action so that the heating power is input by the heating power setting key 31. The lamp 35 is turned off.

  The heating power after the appropriate temperature (FIG. 15B, FIG. 16B) is a state where heating is controlled by the heating power that maintains the temperature of the frying pan, and the heating power is not energized. The heating power is controlled in accordance with the detected temperature of the frying pan between the steps “12” to “12”.

  If no thermal power is input from the thermal power setting key 31 as it is, the heating means 23 is automatically energized within a certain time, for example, 15 minutes, and heating of the frying pan is stopped (FIG. 16 (c)). In addition, when cooking is carried out by putting ingredients in a frying pan, the heating is controlled by the heating power that maintains the temperature of the frying pan, so that the fried food can be made well.

  In the state where heating is controlled with the heating power maintained after the proper temperature, if "strong fire" is input with the heating power setting key 31, the lamp 39 is turned on, the lamp 35 blinks and an instruction is given to input the OFF / START key. To do. At this time, the “appropriate temperature” display displayed on the display 41b is extinguished, and the thermal power stage “10” input on the display 41a is displayed. When turning off / start is input, the lamp 35 is turned on, and the heating of the frying pan is started at a heating power of 2 kW of the stage “10”.

  FIG. 15 shows the relationship between the passage of heating time, the detected temperature at the bottom of the pan, the thermal power, and the thermal power after the thermal power is set along the above flow.

  The frying process has been described above. In all the processes, the temperature detecting element 20 always detects the temperature of the frying pan in addition to the cooking control temperature, and the control means 19 prevents smoke, fire, and frying from being deformed at a high temperature due to abnormal heating. The temperature is controlled by this so that it is fully safe.

  Next, details of the appropriate temperature maintenance control in FIGS. 15B and 16B will be described with reference to FIG. FIG. 17A shows the pot bottom temperature of the pot 501 calculated by the temperature calculation circuit 502 based on the voltage value output from the infrared sensor module 407. In the time t (0) -t (7), the calculated pot bottom temperature shall be in the suitable temperature range. FIG. 17B shows the amount of change per unit time of the pan bottom temperature, which is calculated by the control circuit 503 with a delay of a predetermined unit time. FIG. 17C shows electric power supplied from the high-frequency current supply circuit 405 to the heating coil 200, and is controlled with a predetermined time delay based on the amount of change per unit time of the pan bottom temperature obtained in FIG. Is done.

  As shown in FIG. 17 (a), even when the pan bottom temperature observed by the infrared sensor module 407 is within an appropriate temperature range, the pan bottom temperature fluctuates due to disturbances such as changes in ambient temperature and input of ingredients. There is. In order to maintain the pan bottom temperature in an appropriate temperature range even when such a disturbance occurs, in the induction heating cooker of the present embodiment, the high-frequency current is changed according to the change in the pan bottom temperature calculated by the temperature calculation circuit 502. The high-frequency current supplied from the supply circuit 405 to the heating coil 200 is controlled. For example, as shown in Table 1, when the temperature change amount per unit time is ΔT, it is conceivable to change the thermal power according to the value of ΔT. For example, it is conceivable to control the high-frequency current supply circuit 405 so that the heating power is large when the temperature drop is large, and to control the high-frequency current supply circuit 405 so that the heating power is small when the temperature rise is large. . An example of this is shown in Table 1, but the width of the temperature change amount ΔT used for maintaining the appropriate temperature and the type of thermal power are not limited to those shown in Table 1.

  In addition, as shown in Table 1, it is desirable that the heating power to be used be different between the method for maintaining an appropriate temperature when using an iron pan and the method for maintaining an appropriate temperature when using an aluminum pan. For example, it is desirable that the heating power for maintaining an iron pan at an appropriate temperature is larger than the heating power for maintaining an aluminum pan at an appropriate temperature.

In Table 1, W _Fe (+4)> W _Fe (+3)> W _Fe (+2)> W _Fe (+1)> W _Fe (0)> W _Fe (−1)> W _Fe (−2)> W _Fe (−3)> W _Fe (−4) and W _Al (+4)> W _Al (+3)> W _Al (+2)> W _Al (+1)> W _Al (0)> W _Al (−1 )> W _Al (−2)> W _Al (−3)> W _Al (−4).

  According to the present invention, after preheating is completed, heating is performed with a thermal power that maintains an appropriate temperature until the thermal power is input from the thermal power setting means by the user, so that wasteful use of electric power can be reduced.

  Moreover, since the state heated with the thermal power which maintains the suitable temperature after completion | finish of preheating complete | finishes in a fixed time, even if it forgets that the pan is heated, it is safe and can reduce the wasteful use of electric power.

  Furthermore, after the preheating is finished, the prompting action is performed until the input of the thermal power setting means is made on the display means so as to prompt the input from the thermal power setting means, so that the input of the thermal power setting means can be prevented from being forgotten.

31 Thermal power setting key 34 Menu setting key 104 Top plate 201 Inner peripheral coil 202 Outer peripheral coil 203 Coil bases 301 to 312 Ferrite core 405 High frequency current supply circuit 407 Infrared sensor module 501 Pan 502 Temperature calculation circuit 503 Control circuit

Claims (2)

A top plate for placing an object to be heated;
A heating coil having a concentric gap between the inner and outer coils;
A light-shielding cylinder that is provided in the concentric circular gap and guides the infrared rays emitted from the object to be heated placed on the top plate downward;
An infrared sensor module that outputs a voltage value corresponding to the amount of infrared rays through the light shielding tube;
A temperature calculation circuit for calculating the temperature of the object to be heated based on an output voltage value from the infrared sensor module;
A high-frequency current supply circuit for supplying a current to the heating coil;
A control circuit for controlling the high-frequency current supply circuit based on the output of the temperature calculation circuit ;
A plurality of heating power setting keys for inputting the heating power of the heating coil;
A plurality of lamps provided corresponding to each heating power setting key;
Provided,
The outer circumference of the inner circumference side coil is provided at a distance of about 45 mm from the coil center,
The inner circumference of the outer circumference side coil is provided at a distance of about 55 mm from the coil center,
The light shielding cylinder is provided at a distance of 45 to 55 mm from the coil center,
When the temperature of the object to be heated calculated by the temperature calculation circuit reaches a predetermined temperature , the control circuit notifies the user that the temperature has reached an appropriate temperature, and simultaneously blinks the plurality of lamps. To prompt the user to enter the heating power setting key,
An induction heating cooker characterized by controlling the high-frequency current supply circuit so as to maintain the predetermined temperature while prompting the user to input thermal power . The induction heating cooker according to claim 1,
An induction heating cooker characterized by stopping energization of the heating coil when no thermal power is input from the thermal power setting key within a predetermined time after reaching an appropriate temperature.

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